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    <!-- 使用for循环 - 求出数组元素的和 [5, 8, 9, 2, 1, 5] -->

    <script>

        let arr = [5, 8, 9, 2, 1, 5]

        let num = 0;

        for (let i = 0; i < arr.length; i++) {
            const element = arr[i];
            num+=arr[i]
        }
        alert(num)
    </script>
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